Which from following is a homopolymer ?

A homopolymer is a polymer which is formed from only one type of monomer.

Polyacrylonitrile is formed by the addition polymerization of a single monomer, acrylonitrile.

Buna-N is a copolymer formed from two different monomers, 1,3-butadiene and acrylonitrile.

Urea formaldehyde resin is a condensation copolymer formed from urea and formaldehyde.

Polycarbonate is a condensation copolymer typically formed from bisphenol A and phosgene.

Therefore, polyacrylonitrile is the only homopolymer among the given options.